Deeply engrained in the minds of experienced Western cotton farmers is the heavy whitefly infestation in Arizona and Southern California in the early 1990s which almost brought the industry to extinction over crop stickiness concerns.

The challenge launched more research on improved whitefly control in the West. In fact, the sticky cotton issue led to the birth of integrated pest management (IPM) in Arizona.

“Today, the pest management picture is much clearer by utilizing the primary IPM principles of pest sampling, effective and selective chemical use, and (pest) avoidance,” said Ayman Mostafa, IPM specialist and University of Arizona (UA) assistant area agent serving Maricopa, Pinal, and Pima counties in central Arizona.

Mostafa shared his IPM insight with farmers, pest control advisers, and other industry members during a Summer Ag IPM Workshop held on the Colorado River Indian Tribe Reservation in Poston, Ariz., in late August.

Mostafa noted that IPM advances have reduced pesticide applications in Arizona cotton from an average of 11.5 sprays per season for all cotton pests in the early and mid 1990s to a 1.5 spray average today.

“Some cotton growers haven’t sprayed their fields for lygus bugs or whitefly for the last few years,” Mostafa said.

Natural predator insects can perform a yeoman’s job in lowering pest levels and subsequently reducing or eliminating the need for pesticides. Broad spectrum insecticides are lethal to many enemies. Using selective insecticides under cotton IPM guidelines, when needed, helps conserve natural enemies in Arizona farm fields.    

While traveling to the workshop, Mostafa stopped at a field and captured a wide range of pests and beneficial insects with a sweep net placing them into separate jars. Workshop participants used hand lenses to closely examine the bugs.

“We need to identify natural enemies,” Mostafa said. “If you are sweeping a field and end up with a lot of insects that crawl and fly then we need to train our eyes to know if they are pests or natural enemies by examining the sweep net quickly in the field.”

Among Mostafa’s sweep finds were two chronic cotton pests – lygus and whitefly. Captured natural predators included assassin bugs, Drapetis, Collops beetles, big-eyed bugs, nabid bugs, minute pirate bugs, lacewings, and spiders. These beneficial insects kill pests; thereby reducing yield loss, maintaining crop quality, and keeping more money in farmers’ pockets.

Over the last several months, the UA-sponsored Arizona Pest Management Center has released a series of field crop ‘IPM Shorts’ reports on individual predators. The ‘shorts’ are available online at http://ag.arizona.edu/crops/cotton/agronomic_ipm.html.

However, when pest numbers exceed recommended threshold numbers, pesticides are an important tool for pest control.